The Wall Street Journalreports that 40 of the 100 most delayed flights in the country begin or end in one place.

The dishonorable title goes to Newark Liberty International Airport, according to information from the Bureau of Transportation Statistics. The two flights which are delayed most often at the airport are a 5 p.m. and a 6:25 p.m. Atlanta-bound flight, operated by Delta. Even with an extra 30 minutes padding out the flight time on the 5 p.m. departure, the plane was still late by 30 minutes or more on six of every 10 trips. One of the problems causing such long delays is traffic over Washington D.C., where many of the planes leaving or entering the Northeast create a choke point.

Still, the overall rate of on-time flights has steadily fallen in the past several years: the percentage of flights arriving on time was 76.6% this year through May, the worst in the past three years for the same time period. That drop takes into account a 4.7% decrease in the number of flights (thanks to high fuel prices) in the first five months of 2011. With fewer planes in the air, shouldn’t congestion be less of a problem?

The issue may lie in how airlines schedule flights to the absolute limit of what the FAA legally allows. Delays then cause a ripple effect that lasts for the rest of the day. More and more often airlines are dealing with this domino effect by canceling flights, something that causes even more of headache for them and for passengers.